Date Add/Subtract Calculator — Add or subtract any number of days, weeks, months, or years from a starting date. Useful for figuring out deadlines ("30 days from today"), anniversaries, project timelines, and just about any date math you would otherwise do on a paper calendar.
All math runs in your browser. No date leaves your device.
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Date Add/Subtract Calculatorとは？
Add or subtract any number of days, weeks, months, or years from a starting date. Useful for figuring out deadlines ("30 days from today"), anniversaries, project timelines, and just about any date math you would otherwise do on a paper calendar.
Months and years roll over correctly: January 31 + 1 month = February 28 (or 29 in a leap year). Days and weeks do not care about month length.
使い方
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Pick a starting date
Defaults to today. Edit it freely.
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Choose a unit and amount
Days, weeks, months, years, hours, or minutes. Negative values go backward.
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Read the result
The target date and the number of days between start and target.
使用例
30 days from today
A standard return-window deadline.
結果： Date + 30 days
6 months back
For figuring out a 6-month lookback window.
結果： Date − 6 months
よくある質問
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Last reviewed: 2026-09-25